Photovoltaic solar cells are semiconductor devices which convert sunlight into electricity. Solar cells which utilize crystalline semiconductors, such as silicon, offer the advantages of high performance and reliability. Until recently, expanded utilization of crystalline silicon solar cells has been limited by the high cost of the solar cells. Significant reductions in the cost of solar cells can be achieved by using thin-film solar cells such as the "SILICON-FILM" cell described by A. M. Barnett et al in U.S. Pat. No. 5,057,163, which is incorporated by reference herein.
As pointed out by Warner in U.S. Pat. No. 3,994,012, which issued Nov. 23, 1976 and is incorporated by reference herein, it has been generally recognized that a plurality of individual silicon solar cells must be connected in series in order to produce a photovoltaic module having the desired output voltage. Present technology of silicon module assembly involves stringing together of as many as 36 individual solar cells. Furthermore, present approaches require that electrical contacts be made to opposite sides of each solar cell. As further noted by Warner, some of these difficulties can be overcome by configuring a monolithic array of solar cells. However, monolithic designs known in the art are generally expensive to manufacture, are expected to reduce power output due to losses in active area and are not useful with thin crystalline silicon solar cells. These characteristics, when combined with the high cost of conventional thick crystalline silicon solar cells, contribute to the cost and performance limitations that inhibit utilization of silicon photovoltaic modules on a wider scale. Accordingly, there is a need for a monolithic photovoltaic module made up of submodules formed from thin crystalline silicon solar cells which are connected in series on a single substrate.